Monitoring systems for the railroad industry provide methods and apparatus for detection of objects hanging from and dragging beneath a train as the train travels along rails of a railroad track. Dragging equipment detection systems are typically placed at twenty mile intervals over long stretches of a railroad track, in conjunction with other defect detection equipment. If a dragging object is detected, the train is stopped so that the object can be secured to reduce the potential for derailment or other problems.
One problem associated with existing dragging equipment detection systems involves the maintenance and adjustment required by the systems for continued proper operation. Existing systems include an impact element mounted on a shaft extending generally between the rails. The impact element includes at least one surface that is located and oriented to be impacted by an object hanging down from a passing train. Impact of an object against the impact element causes the shaft to rotate, and the rotational motion of the shaft is translated into linear motion used to actuate a switching mechanism and energize an alarm. The moving parts of the switching mechanism require lubrication and adjustment.
One attempt to reduce the amount of maintenance and adjustment of dragging equipment detection systems is disclosed in U.S. Pat. No. 7,292,144 of Ballinger that issued on Nov. 6, 2007 (the '144 patent). The '144 patent provides a contact-less switching mechanism wherein a magnetic amplifier and a magnet are moved relative to each other to generate an output signal indicative of an object impacting an impact element. The output signal is a function of variations in the impedance of a circuit connected to the magnetic amplifier caused by moving the magnetic field of the magnet closer to and farther away from the magnetic amplifier.
Although the dragging equipment detection system of the '144 patent may help to reduce the amount of maintenance required to keep the system and the switching mechanism working properly, it may be less than optimal. In particular, it may be necessary to undertake the time-consuming process of calibrating the detector by periodically adjusting the distance between the magnetic amplifier and the magnet to generate a desired output signal when the impact element has been moved a certain amount by an impact.
The system and method of the present disclosure solves one or more problems set forth above and/or other problems in the art.